THE   UNIVERSITY 

OF  ILLINOIS 

LIBRARY 


A6RIGDLTURAL. 
LIBRARY 


UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN  NO.  222 


FIELD  EXPERIMENTS  IN  SPRAYING  APPLE 

ORCHARDS  FOR  THE  CONTROL 

OF  APPLE  BLOTCH 


BY  A.  J.  GUNDEKSON 


CONTENTS  OF  BULLETIN  No.  222 

PAGE 

INTRODUCTION 551 

Objects  551 

Location  and  Description  of  Orchard 551 

Apparatus  and  Preparation  of  Materials 552 

Method  of  Eecording  Results 552 

Weather  Conditions  as  Affecting  Blotch 553 

EXPERIMENTS  IN   1916 553 

Relative  Values  of  Bordeaux  and  Lime  Sulfur 553 

Value  of  Different  Applications  of  Bordeaux  and  Lime  Sulfur 555 

Effect  of  Interchanging  Bordeaux  and  Lime  Sulfur 559 

Summary  of  Results  for  1916 560 

Incidental  Observations    561 

EXPERIMENTS  IN.  1917 561 

Effect  of  Dormant  Applications  of  Copper  Sulfate,  Scalecide,  Lime  Sul- 
fur, and  Lime-Sulfur  Copper-Sulf ate  Mixture 563 

Relative  Values  of  Bordeaux  and  Lime  Sulfur 563 

Value  of  Different  Applications  of  Bordeaux  and  Lime  Sulfur 565 

Affect  of  the  Addition  of  Arsenate  of  Lead  to  Lime  Sulfur 568 

Relative  Merits  of  Dusting  and  Liquid  Spraying.  568 

Summary  of  Results  for  1917 570 

Incidental  Observations    570 

EXPERIMENTS  IN   1918 571 

Relative  Values  of  Bordeaux  and  Lime  Sulfur 571 

Value  of  Different  Applications  of  Bordeaux  and  Lime  Sulfur 573 

Summary  of  Results  for  1918 573 

Incidental  Observations    573 

RECOMMENDATIONS  FOR  THE  CONTROL  OF  APPLE  BLOTCH.  .  .  .575 


FIELD  EXPERIMENTS  IN  SPRAYING  APPLE 

ORCHARDS  FOR  THE  CONTROL 

OF  APPLE  BLOTCH 

BY  A.  J.  GUNDERSON,  ASSOCIATE  IN  POMOLOGY 

INTRODUCTION 

Apple  blotch  is  the  most  destructive  fungous  disease  of  apple 
orchards  in  southern  Illinois  and  during  the  past  few  seasons  obser- 
vations have  disclosed  its  presence  in  certain  apple  orchards  of  central 
and  western  Illinois.  There  is  no  question  but  that  blotch  is  spread- 
ing northward  but  it  is  doubtful  if  the  orchards  of  northern  Illinois 
will  ever  become  seriously  infected. 

Damage  caused  by  apple  blotch  is  two-fold,  consisting  in  injury 
to  the  fruit  in  the  form  of  spotting,  which  reduces  its  commercial 
value,  and  in  canker  infection  of  small  limbs,  twigs,  and  fruit  spurs, 
which  reduces  the  productiveness  of  the  trees.  Infection  of  the  wood 
is  actually  killing  hundreds  of  Duchess  apple  trees  in  southern  Illi- 
nois and  in  a  large  measure  is  responsible  for  the  weakened  and  un- 
productive condition  of  hundreds  of  Ben  Davis  .and  Gano  trees  in  the 
southern  counties  of  the  state. 

In  view  of  such  conditions  it  was  considered  important  that  meth- 
ods of  spraying  for  the  control  of  apple  blotch  be  tested. 

OBJECTS 

Spraying  experiments  on  the  control  of  apple  blotch  were  carried 
on  during  the  years  1916,  1917,  and  1918  at  Flora.  The  chief  objects 
of  these  investigations  were  to  study  the  following  points  in  the  con- 
trol of  blotch:  (1)  the  relative  values  of  Bordeaux  and  lime  sulfur; 

(2)  the  value  of  different  applications  of  Bordeaux  and  lime  sulfur; 

(3)  the  effect  of  interchanging  Bordeaux  and  lime  sulfur;    (4)  the 
effect  of  dormant  applications  of  copper  sulfate,  Scalecide,  lime  sulfur, 
and  a  combination  of  lime  sulfur  and  copper  sulfate;    (5)  the  effect 
of  the  addition  of  arsenate  of  lead  to  lime  sulfur;  and  (6)  the  rela- 
tive values  of  dusting  and  spraying. 

LOCATION  AND  DESCRIPTION  OF  ORCHARD 

Experiments  were  conducted  in  the  Suggett  orchard,  located  about 
one  and  one-half  miles  southeast  of  Flora.  The  orchard  consisted  of 
thirty-eight  acres  of  eighteen-year-old  Ben  Davis.  At  the  beginning 

551 


552  BULLETIN   No.   222  [September, 

of  the  work  in  1916  the  trees  were  in  very  poor  condition,  owing  to 
lack  of  nutrition,  diseases,  and  the  fact  that  no  spraying  or  pruning 
had  been  done  for  years.  The  result  was  that  every  tree  in  the  orchard 
was  seriously  infected  with  apple  blotch,  cankers  appearing  on  twigs, 
water  sprouts,  and  fruit  spurs.  Bitter-rot  and  black-rot  cankers  were 
also  present  to  some  extent.  The  tops  of  the  trees  were  very  dense 
and  contained  considerable  dead  wood. 

In  laying  out  the  experiments,  the  orchard  was  divided  into  plats 
containing  four  trees  each,  except  in  the  case  of  the  dusted  plat,  which 
contained  twenty-six  trees.  A  check,  or  unsprayed,  row  was  left  thru 
the  entire  length  of  the  orchard. 

APPARATUS  AND  PREPARATION  OF  MATERIALS 

Whenever  Bordeaux  was  used  in  these  treatments  it  was  made  ac- 
cording to  the  following  formula:  6  pounds  of  copper  sulfate  and 
8  pounds  of  lime  in  100  gallons  of  water. 

For  dormant  spraying,  copper  sulfate  was  used  at  the  rate  of  8 
pounds  in  100  gallons  of  water;  commercial  lime  sulfur  at  the  rate 
of  11  gallons  in  100  gallons  of  water;  Scalecide  at  the  rate  of  6 
gallons  in  100  gallons  of  water ;  and  lime-sulfur  and  copper-sulf ate 
mixture  at  the  rate  of  11  gallons  of  commercial  lime  sulfur  and  8 
pounds  of  copper  sulfate  in  100  gallons  of  water. 

For  summer  spraying  commercial  sulfur  was  used  at  the  rate  of 
2,1/2  gallons  in  100  gallons  of  water.  Powdered  arsenate  of  lead  was 
used  at  the  rate  of  2  pounds  in  100  gallons  of  water.  The  dust 
mixture  used  was  composed  of  85  percent  superfine  sulfur  and  15 
percent  powdered  arsenate  of  lead. 

During  1916  all  sprays  were  applied  with  a  Hardie  No.  32  hand 
outfit,  at  about  125  pounds  pressure.  In  1917  and  1918,  a  triplex 
Bean  sprayer  was  used  with  pressure  ranging  from  175  to  250  pounds. 
During  1916  and  1917,  rods  and  disc  nozzles  were  used  in  spraying 
the  trees,  while  in  1918  spraying  was  done  from  the  ground  with  a 
Bean  spray  gun,  and  from  the  tower  with  rod  and  disc  nozzles.  Severe 
lime-sulfur  injury  to  foliage  due  to  drenching  with  the  spray  gun 
resulted  in  discontinuing  its  use  after  the  first  three  summer  sprays 
had  been  applied.  The  dust  was  applied  by  means  of  a  dusting 
machine  of  small  type  driven  by  a  11/2  horse-power  engine. 

METHOD  OF  EECORDING  RESULTS 

Records  were  kept  thruout  the  season  on  the  appearance  of  the 
foliage  with  regard  to  fungi,  insects,  spray  injury,  and  vigor.  At 
harvest  time  two  representative  trees  from  each  sprayed  plat  were 
picked  and  all  the  apples  placed  on  a  sorting  table  and  counted. 
From  these,  two  hundred  apples  were  chosen  at  random  and  carefully 


1919]  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  553 

examined.  The  fruit  from  three  representative  unsprayed  trees,  one 
at  each  end  and  one  in  the  center  of  the  check  row,  was  similarly 
handled,  and  the  results  averaged. 

WEATHER  CONDITIONS  AS  AFFECTING  BLOTCH 

Weather  conditions  affect  the  development  of  most  fungous  dis- 
eases. Differences  of  opinion  exist,  however,  as  to  what  conditions 
are  most  favorable  to  blotch  development.  Scott  and  Rorer  claim 
that  blotch  develops  in  cool  or  warm  weather,  but  that  rains  or  heavy 
dews  are  necessary  to  the  germination  of  the  spores  and  their  spread 
from  cankers  to  the  fruit.  Lewis  states  that  blotch  develops  equally 
well  in  either  dry  or  wet  weather,  but  says  nothing  about  the  effect 
of  rain  upon  spore  dissemination. 

During  1916  and  1918  frequent  showers  occurred  at  Flora  during 
the  period  from  four  to  six  weeks  after  the  fall  of  the  bloom.  In  these 
years  blotch  infection  on  unsprayed  trees  was  93.24  and  94.0  percent 
respectively.  During  the  same  period  in  19l7,  little  rain  fell  and 
blotch  infection  on  unsprayed  trees  was  75.5  percent.  Certain  com- 
mercial orchards  in  southern  Illinois  appeared  to  have  less  blotch  on 
the  fruit  in  1917  than  in  1916  and  1918.  During  the  period  from  four 
to  six  weeks  after  the  fall  of  the  bloom  in  1916,  1917,  and  1918,  the 
temperature  at  Flora  averaged  between  65  and  70  degrees.  The 
amount  and  frequency  of  the  rainfall,  therefore,  appeared  to  be  the 
factor  which  caused  greater  dissemination  of  spores  and  offered  excel- 
lent conditions  for  their  growth. 

During  the  season  of  1918  frequent  rains  prevented  a  good  deal 
of  spraying  in  commercial  orchards  in  central  and  southern  ^Illinois, 
with  the  result  that  there  was  unusual  opportunity  for  Hotch  infec- 
tion and  the  disease  actually  proved  very  serious.  Then,  too,  such 
rains  rendered  the  sprays  that  were  applied  less  effective. 

EXPERIMENTS  IN  1916 

Experiments  in  1916  were  conducted  with  reference  to:  (1)  the 
relative  values  of  Bordeaux  and  lime  sulfur  as  sprays  for  blotch; 
(2)  the  value  of  different  applications  of  Bordeaux  and  lime  sulfur 
as  sprays  for  blotch;  and  (3)  the  effect  on  blotch  control  of  inter- 
changing Bordeaux  and  lime  sulfur. 

RELATIVE  VALUES  OF  BORDEAUX  AND  LIME  SULFUR 

Spraying  investigations,  previously  conducted,  both  in  Illinois,  and 
in  other  states,  had  shown  Bordeaux  to  be  from  slightly  to  consid- 


554 


BULLETIN   No.   222 


[September, 


S 

.5° 

O        t-               O         CO         O 
O         i-J               O         04         O 
04'                           r-i 

e 

co 

1 

pq 

to 

3 
O 

§00               O         i-l         O 
O               O         in         O 

£ 

•C 

0 
CO 

T-H 

OQ 
00  <M 

tt> 

as  o  w 

s  g^ 

01 

03 
03 

tuo 

•s 

I 

co 

IO         GO               O>         O4         CO 
b-         i—l                i—  1         t-         b- 

CO          iH                O         O4          i—  1 
Tt<         04                •*          04         O4 

jf-5"^ 

OJ 

w 

QJ     ^     C* 

Percent 

M 

erious 

t-;         T);               04         00         ITS 

i—  1 

^•g  ^ 

0          =H 

.-H  1=3  o 

02 

'H^^ 

3 

I 

CO         34               CD     '    00         •* 
b-         r-J               O         CO         04 

B  J>   fti 

fi  aj 

i 
p 

> 

5 

oi       04'           CD'      co       co 

i—  1         TjH                i-l         b-         O5 

03       <H 

00    03 

DO   _^J 

n\    at    m 

i 
i 

O    ^ 

( 

j  »— 

03    03    a 

K 

r     i 

H 

04         00               04         00         C4 

>    P*-    W 

< 

H     P 

l| 

f- 

-     « 

CO          iH                 -^    .      C4          OO 
CO          CO                  •*          CO          I-l 

..            „ 

-* 
< 

J    G 

TJH  in  to 

E 

•it 

'e 

H 

CO         CO               CO         CO 

S 

.2 

KM                 ^           ^         03 

Is 

-                                                     0 

•^ 

CO         CO                CO         CO         ^r 

s 

rH                f~i          i~H                ^H 

C4 

03* 

_ 



CO 

"3 

o3     *         o3         o3     *         o3 

J 

S    'pj               rS               "Is               " 

o 

«H    ®         <H         «H    *         «H 

in  -—I 

•4J 

O  ^          0          O*^1          0 

04         13 

g 

jD^          0         ^  ^          <D 

04    ^>«H 

Treatm 

H    -4-J.              ^                P    -4-3                C 

03    e8            03           03    03            03 

£  g      2      2  g      2 

03    nj         03         w    ro         03         +3 

ft     *w 

CH    ^          <H          «H    (KJ          <H            S 

-I  ^1 

33       3       "3Pi       "3       "S 
M    03          to          •   •          cfi          0) 

S*o  0 

03                                  03                          ^ 

03  r73             03            03  1-^3             Q?           ^_> 

B  "9  9 

||           |           ||           |           || 

..*.. 

2 

Jl 

b-               rH         CO               C4          03 

r-l  O3  CO 

H 

1919]  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  555 

erably  more  effective  than  lime  sulfur  in  the  control  of  blotch.1  Such 
results,  however,  could  not  be  considered  complete.  The  fact  that  lime 
sulfur  in  some  cases  had  given  good  results,  altho  not  equal  to  those 
from  Bordeaux,  made  further  comparative  tests  of  these  materials 
advisable.  Then,  too,  the  injurious  effect  of  Bordeaux  upon  the  fruit, 
following  applications  against  blotch  in  southern  Illinois  orchards, 
emphasized  the  need  of  an  effective  substitute. 

As  a  further  test  of  the  relative  values  of  Bordeaux  and  lime  sul- 
fur as  sprays  for  blotch  on  Ben  Davis  in  southern  Illinois,  the  plats 
were  sprayed  with  these  materials  as  shown  in  Table  1. 

The  data  presented  show  that  Bordeaux  was  decidedly  superior  to 
lime  sulfur  in  the  control  of  blotch.  In  Plat  7,  where  Bordeaux  was 
applied  three,  five,  seven  and  ten  weeks  after  the  fall  of  the  petals, 
there  was  12.73  percent  blotch,  as  compared  with  42.12  percent  blotch 
on  Plat  11,  which  was  sprayed  with  lime  sulfur  at  the  same  periods. 
A  similar  comparison  is  presented  between  Plat  6,  which  was  sprayed 
with  Bordeaux  three,  five,  and  ten  weeks  after  the  fall  of  the  petals, 
resulting  in  16.06  percent  blotch,  and  Plat  12,  which  was  sprayed 
with  lime  sulfur  at  these  three  periods,  and  showed  73.68  percent 
blotch.  The  unsprayed  row  showed  93.24  percent  blotch. 

Very  usual  differences  between  the  effect  of  the  two  sprays  upon 
the  fruit  is  shown  in  the  russet  column.  Plats  11  and  12,  which  were 
sprayed  with  lime  sulfur,  alone,  show  about  the  same  percentage  of 
russet  as  the  unsprayed  row.  It  may  be  concluded,  therefore,  that 
something  other  than  the  spray  russetted  the  fruit.  As  regards 
Plats  6  and  7,  which  were  sprayed  with  Bordeaux  three  and  four 
times,  respectively,  it  will  be  noted,  after  subtracting  the  amount  of 
russet  on  the  unsprayed  row,  that  the  Bordeaux  caused  a  good  deal 
of  russet. 

Plats  11  and  12  show  a  small  percentage  of  lime-sulfur  burn.  This 
developed  a  few  days  following  the  application  of  lime  sulfur  arsen- 
ate  of  lead  made  in  mid-July,  when  the  temperature  was  extremely 
high.  It  occurred  on  the  fruit  which  had  received  too  much  spray 
and  was  therefore  confined  to  scattered  areas  of  the  trees. 


Scott  and  Korer  found,  from  investigations  carried  on  in  Arkan- 
sas during  1907.  that  the  principal  blotch  infection  on  apples  occurred 
from  four  to  six  weeks  after  the  fall  of  the  petals,  and  that  scattering 
infections  continued  to  take  place  thruout  the  season.2  They  recom- 


1U.  S.  Dept.  Agr.  Bur.  Plant  Indus.  Circ.   54,  p.   13.     1910.     Kans.  Agr. 
Exp.  Sta.  Bui.  196.     1913.     111.  Agr.  Exp.  Sta.  Bui.  185,  p.  111.     1916. 
2U.  S.  Dept.  Agr.  Bur.  Plant  Indus.  Bui.  144,  p.  21.    1909. 


556 


BULLETIN  No.   222 


[September, 


!_| 

1 

w 
000*00000 

rH 

S 

02 

M 

3 

m 

0 

eo 

OOOOOOOO 

(M 
(M 

PH 

i 

•rH 
rH 

O 

00    §M 

EH 

rQ 

4)    P 

•( 

rrH. 

PI    *~3      r»> 

03 

ro 

1 

<v 

I 

rH               OS               rH               O               SO               rH               t-jt>- 

,?'3Hl 

a 

i 

ri 
<» 

1 

03 

SSSS^^^S 

111 

H 

be 

CO 

OH 

cc 

o  P^ 

H 

M 

03 

*Q    r—  1    *H 

W 

§ 

P 

ICOrHrHt-jCJJt-jW 

•—  i  'S  ° 

S 

E 

'C 

Oq               <jq               cq               CQ               rH               O5               IO05 

3  •  *l 

H 

0> 

O 

I—  1                                    rH 

*H          r-H      pjT 

PM 

03 

OJ   Ktj      i^ 

g 

^ 

3 

1*1 

M 

-4 

! 

OJ                rH                t-.                QO                OJ                O                t>;         cjq 

ri  to  cj 

P 
1 

P 

3 

§CO                 Oi                 t—                 rH                 CO                 CQ          CO 
t-                »O                r(H                W                rH                rH         OJ 

III 

P  fl  ts 

0 

0 

i  . 

CD    O     _ 

.>  >  g 

a 

• 

o 

i 

HH  02  fcH 

* 

j 

5  £ 

« 
ii 

3  -    iS       A       SB       .£i       £       8    S 

..  ••   •• 

^ 

H      ° 

»OCNieOCOrHOS5OOD 

IO  ^O  t^> 

g 

13  T 

^  c 

i 

TH                 CO                                       CO                 10                                       CO          rH 

s 

E 

H  ^ 

i 
i 

LJ 

"j 

t, 

OQ 

M 

m 

r-H 

hH 

S 

to                                      «T 

fe 

O 

10          io"                          10*         »o" 

0 

.rH 

-M 

•>                  -.                     ^                    •>                  r>          05 

03 

ri 

0 

fc 

•t-H 

Q 

IO 

ft 

(M               (M               O9               CQ               C4               Oq               09 

M 

0 

13 

7.1 

PL, 

^•f 

EH 

:   j  i   j  !   J  !   J  i   J  :   J  i     : 

73  P< 

1 

j        ^    *        ri     *        ri    *        ri     *        ri    * 

'Q  «H 

ft  o 

«H  rj 

ft 

1 

^jO          ^jO          .JjO          ^jO          4J®          HJ                 5 

'^9 

O 

H 

a  2      0-2      S-2      o-2      S-2      o-2      s-2 

'C  S  *H  -2 

03 

ri 

g2       gS       gfl       gfl       go       gS       ma 

-5*     •*  ^*  *rf 

EH 
O 

EH 

H§       t3§       bS       bS      bS      faS      fa§ 

WQQ                 rigQ                 rigQ                 riQQ                 "QQ                 ™CQ                 ^*CD                -*^ 
rH                             ^                               rH                 L,j3                 rHM                 rHrS                 rHB?                 " 

rrT-t^    ri  r^J 
3    <»          Q> 

f 

'•-'b.i       "HM       "HVI       "t-ivi       ''-'M       ''-'M       **-<*>        S 
33      rgg      "38      3s      33      33      '"S      ** 

rH    *H     ri 

| 

oori        cnri        cori        ccri        mri        cori        oori        c-1 

QJ    O  fr^    ^ 

O)            (D0*           flj"           ffl®            OJ**            O)W            (D*1           *" 

"™    r-l      -H      W 

i 

gb        S*-1        S^        S'-1        SM        S^        S^1 
.So      .So      .So      .So      .So      .So      .So       o 

JPQ          r^PQ          JW          rHPQ          rHPQ          ^PQ          rnPQ          r?H 

sg^S 

•< 

_l_3 

TJ 

rH  <M  CO  •* 

• 

B 

S 

t-t          09           eo          •*           »o           to          t- 

€ 

li)19]  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  or  BLOTCH  557 

mended  applying  four  sprays  of  Bordeaux:  the  first,  three  to  four 
weeks  after  the  fall  of  the  petals;  a  second  about  four  weeks  later; 
and  a  third  and  fourth  at  three-week  intervals  thereafter.  The  pur- 
pose of  these  applications  was  to  keep  the  fruit  well  coated  with  spray 
until  picking  time.  The  number  of  applications,  however,  would  de- 
pend upon  the  season,  a  wet  one  requiring  more  sprays  than  a  dry 
one.  Lewis  has  reported  that  in  Kansas  the  greatest  blotch  infection 
occurs  from  four  to  six  weeks  after  the  fall  of  the  petals,  and  con- 
tinues during  the  remainder  of  the  growing  season,  or  at  least  until 
the  last  of  August.1  He  recommended  the  use  of  Bordeaux  during 
dry  weather  and  lime  sulfur  in  a  wet  season,  to  be  applied  three,  five 
to  seven,  and  ten  weeks  after  the  fall  of'  the  petals. 

For  the  purpose  of  gaining  information  on  the  value  of  different 
applications  of  Bordeaux  and  lime  sulfur  as  sprays  for  blotch  under 
conditions  in  southern  Illinois,  plats  were  sprayed  with  these  materials 
as  shown  in  Table  2.  It  will  be  noted  that  sprays  applied  at  the 
cluster-bud  stage,  at  the  fall  of  the  petals,  and  ten  weeks  thereafter 
were  the  same  for  all  plats,  as  it  was  the  purpose  to  compare  the  val- 
ues of  only  the  other  applications. 

The  data  presented  for  Plat  1  show  that  where  lime  sulfur  was 
applied  ten  days  after  the  fall  of  the  petals,  90.99  percent  blotch 
developed  on  the  fruit.  When  comparison  of  this  figure  is  made  with 
the  percentage  of  blotch  present  on  the  unsprayed  row,  93.24  percent, 
it  will  be  seen  that  lime  sulfur  applied  ten  days  after  the  fall  of  the 
petals  was  practically  of  no  value  in  controlling  blotch.  Plat  2, 
sprayed  with  lime  sulfur  three  weeks  after  the  fall  of  the  petals, 
shows  73.12  percent  blotch,  which  in  comparison  with  the  amount  on 
the  unsprayed  row  represents  a  control  of  20.12  percent.  Plat  3, 
sprayed  with  lime  sulfur  three  and  five  weeks  after  the  fall  of  the 
petals,  shows  59.78  percent  blotch,  or  33.46  percent  control,  of  which 
20.12  percent  may  be  attributed  to  the  spray  three  weeks  after  the 
fall  of  the  petals,  leaving  13.34  percent  control  due  directly  to  the 
five-weeks  spray.  Plat  4,  which  received  lime  sulfur  three,  five,  and 
seven  weeks  after  the  fall  of  the  petals,  shows  47.84  percent  blotch, 
or  45.40  percent  control.  Since  33.46  percent  control  was  exerted  by 
the  three  and  five  weeks  sprays  of  lime  sulfur,  it  may  be  concluded 
that  lime  sulfur  applied  seven  weeks  after  the  fall  of  the  petals  con- 
trols blotch  to  the  extent  of  11.94  percent. 

Plat  5,  sprayed  with  Bordeaux  three  weeks  after  the  fall  of  the 
petals,  shows  51.97  percent  blotch,  or  41.27  percent  control.  Plat  6, 
where  Bordeaux  was  applied  three  and  five  weeks  after  the  fall  of  the 
petals,  shows  16.06  percent  blotch,  or  77.18  percent  control.  "  Since 


JKans.  Agr.  Exp.  Sta.  Bui.  196.    1913. 


558 


BULLETIN  No.  222 


[September, 


-u 

§ 

If) 

eo' 

OS 

o 
ci 

o 

rH 

.' 

53 

I-H 

0> 
G> 

09 

oo 

b- 

eo 
>o 

o 

o 

b- 

eo 

OS  <M 

03 

^ 

1O 

oi 

ca 

c<i 

O  ^ 

1 

02 

iH 

3    §    >> 

OJ 

u 
h 

£ 

s 

CO 

t- 

3 

oq 

ca 

oTrS  *^ 

03  5    nT 

"®  &3 

"o 

ea 

oi 

co* 

eo 

*i_i  **^    CL 

s 

iH 

5| 

eo 

os 

0    °«H 

,_,  S    0 

^i  a>  ^ 

o  •*->   u 

-*3  «H    S 

*H    03   -*^ 

< 

5    —  - 

o3        *w 

Si 

H     Jg 

CD 

os 
oo 

oo 

CM 

rH 

oo   o3 
oo  M 

•H 

10 

00 

QJ     O     M 

s 
H 
( 

|l> 

eo 

.    "* 

<• 

T-H 

CD     >•     O 

1      g 

& 

H    O 

0    P 

'ft 

CO    O)    _. 
>    >    0 

•rt  o  a> 

•<*  IO  CO 

la 

PI 

CO 

CO 

co 

.2 

irT 

10" 

wT 

0 

0 

•*f 

•^ 

•^ 

O 

^3 

e»T 

eo 

eo" 

fc 

4 

" 

c<T 

T-T 

of 

r-T 

co 
ca 

r-      • 
S  73 

§• 
73 

e8     • 

O>  73 

£ 

"   CS 

•-1    cS 

1-1    03 

"3 

"a 

O  "" 

O  I~* 

O  ~ 

V 

B 

<H 

i 

41 

®    0 

-2  ° 

-2  ° 

e«  05 

o 

S3 

E 
H 

—  *-> 
£    =« 

2-  o 
3  £ 

—  — 

0   03 
£    a 

«  s 

s  "S 

£  a 
«  £ 

•+J 

CO  — 

00      13 
ca  ^^2 

^    C8  ^ 

*    rt 
3    ra 

i!    « 

gS 

a  « 

3* 
S    M 

= 
o 

B 

«| 

3    3 

00     Cj 

^  3 

ic    n 

3    3 
oo    o3 

"S 

a> 

-3  " 

§3 

.§  o 

B 

W  T3 

.§s 

0^ 
I] 

E 

-4J 

o 

|5f 

JCQ 

UW 

a  ca 

*Z 

^  °  o 

ta 

o 

03 

•_ 

GQ   t—  ]     ^ 

I—  1 

I 

rH  cq  eo 

1919}  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  SS9 

41.27  percent  control  was  exerted  by  the  three  weeks  spray,  Bordeaux 
applied  five  weeks  after  the  fall  of  the  petals  actually  gave  35.91  per- 
cent control.  On  Plat  7,  where  Bordeaux  was  applied  three,  five,  and 
seven  weeks  after  the  fall  of  the  petals,  there  was  12.73  percent  blotch, 
or  80.51  percent  control.  Since  the  three-  and  five-weeks  sprays  of 
Bordeaux  gave  a  combined  control  of  77.18  percent,  the  actual  blotch 
control  exerted  by  the  seven  weeks  spray  was  3.33  percent. 

In  percentages  of  russet  present  important  differences  appear  be- 
tween the  effects  of  lime  sulfur  and  of  Bordeaux.  It  will  be  noted 
that  the  percentages  present  in  Plats  1,  2,  3,  and  4,  sprayed  with 
lime  sulfur,  were  very  nearly  the  same  as  the  percentage  present  on 
the  unsprayed  row ;  hence  the  conclusion  is  that  something  other  than 
the  sprays  caused  this  injury.  Reference  to  Plats  5,  6,  and  7  will 
show  that  considerable  russet  appeared  on  the  fruit.  Since  it  was 
observed  in  the  orchard  that  russeting  of  the  fruit  occurred  prior  to 
July  1,  and  since  Plat  5,  sprayed  with  Bordeaux  three  weeks  after  the 
fall  of  the  petals,  showed  more  russet  than  was  present  on  Plat  6  and 
almost  as  much  as  was  present  on  Plat  7,  it  may  be  concluded  that 
the  application  of  Bordeaux  three  weeks  after  the  fall  of  the  petals 
caused  the  russet  on  all  of  the  plats  minus  the  percentage  which  ap- 
peared on  the  unsprayed  row. 

It  will  be  noted  that  no  burn  appeared  on  Plats  1,  2,  or  3,  but  that 
a  small  amount  appeared  on  Plat  4,  due  to  lime  sulfur  arsenate  of 
lead  applied  seven  weeks  after  the  fall  of  the  petals  during  very  hot, 
dry  weather. 

EFFECT  OF  INTERCHANGING  BORDEAUX  AND  LIME  SULFUR 

During  the  wet  season  of  1915  certain  growers  in  southern  Illinois 
reported  serious  russeting  of  fruit  even  tho  Bordeaux  had  been  used 
three  weeks  after  the  fall  of  the  petals,  and  even  later.  Such  an 
occurrence  is  rare,  altho  experiments  conducted  by  this  station  in 
1912  showed  that  Bordeaux  applied  three  weeks  after  the  fall  of  the 
petals  caused  33.1  percent  slight  russet.1  Investigations  on  the  con- 
trol of  blotch  have  shown  that  the  first  and  most  important  spray  is 
the  one  applied  three  or  four  weeks  after  the  fall  of  petals.2  Since 
russetting  of  the  fruit  may  follow  such  an  application  and  applications 
made  still  later,  it  was  thought  that  lime  sulfur,  which  usually  does 
not  cause  russet,  might  be  substituted  for  Bordeaux  at  these  times. 
Accordingly  sprays  were  applied  as  shown  in  Table  3.  The  first,  sec- 
ond, and  sixth  applications  were  the  same  in  all  plats. 


'HI.  Agr.  Exp.  Sta.  Bui.  185,  p.  179.    1916. 

2U.  S.  Dept.  Agr.  Bur.  Plant.    Bui.  144,  p.  22.    1909.     Kans.  Agr.  Exp.  Sta. 
Bui.  196,  p.  572.    1913. 


560  BULLETIN  No.  222  [September, 

The  results  show  that  in  Plat  7,  where  Bordeaux  was  applied 
three,  five,  and  seven  weeks  after  the  fall  of  the  petals,  there  was  12.73 
percent  blotch.  In  Plat  10,  where  lime  sulfur  was  substituted  for 
Bordeaux  in  the  spray  three  weeks  after  the  fall  of  the  petals,  there 
was  49.49  percent  blotch.  In  Plat  9,  where  lime  sulfur  was  sub- 
stituted for  Bordeaux  in  the  sprays  three  and  five  weeks  after  the 
fall  of  the  petals,  there  was  36.86  percent  blotch.  These  results  show 
that  lime  sulfur  did  not  control  blotch  as  well  as  Bordeaux  when 
substituted  for  the  latter  spray  either  three  or  five  weeks  after  the 
fall  of  the  petals. 

It  will  be  noted  that  in  Plat  10  the  substitution  of  lime  sulfur 
for  Bordeaux  in  the  spray  three  weeks  after  the  fall  of  the  petals 
eliminated  the  russet  factor  but  did  not  satisfactorily  control  blotch. 
The  same  is  true  for  Plat  9,  where  lime  sulfur  was  substituted  for 
Bordeaux  in  the  sprays  applied  three  and  five  weeks  after  the  fall 
of  the  petals.  The  russet  present  on  the  fruit  of  Plats  9  and  10 
was  caused  by  something  other  than  the  sprays,  since  the  unsprayed 
row  shows  2.57  percent  serious  and  21.76  slight  russet.  By  sub- 
tracting these  amounts  from  the  percent  of  russet  for  Plat  7,  it 
will  be  found  that  Bordeaux  applied  three  weeks  after  the  fall  of 
the  petals  actually  caused  13.21  percent  serious  and  21.99  percent 
slight  russet. 

SUMMARY  OF  RESULTS  FOB  1916 

1.  Bordeaux  proved  superior  to  lime  sulfur  as  a  spray  for 
blotch. 

2.  The  most  important  sprays  in  the  control  of  blotch  were  those 
applied  three  and  five  weeks  after  the  fall  of  the  petals ;  when  applied 
seven  weeks  after  the  fall  of  the  petals  these  sprays  were  of  less 
value.     Lime  sulfur  applied  ten  days  after  the  fall  of  the  petals 
failed  to  exert  any  control  over  blotch. 

3.  Individual  sprays  of  Bordeaux  applied  three,  five,  or  seven 
weeks  after  the  fall  of  the  petals  proved  superior  to  similar  indi- 
vidual applications  of  lime  sulfur.     This  superiority  may  have  been 
due  to  the  greater  adhesiveness  of  Bordeaux. 

4.  Bordeaux  applied  three  weeks  after  the  fall  of  the  petals 
russetted  the  fruit. 

5.  The  substitution  of  lime  sulfur  for  .Bordeaux  three  or  five 
weeks  after  the  fall  of  the  petals  eliminated  russet  but  failed  to 
control  blotch.    The  russet  caused  by  Bordeaux  applied  three  weeks 
after  the  fall  of  the  petals  was  less  injurious  to  the  quality  and  the 
appearance  of  the  fruit  than  was  the  increase  in  amount  of  blotch 
caused  by  substituting  lime  sulfur  for  Bordeaux  at  this  application. 


SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  561 

INCIDENTAL  OBSERVATIONS 

1.  Blotch  appeared  on  the  fruit  of  the  unsprayed  row  about 
June  15,  six  weeks  after  the  fall  of  the  petals.    Later  in  the  season 
it  was  detected  on  the  foliage  both  of  unsprayed  and  of  sprayed  trees, 
particularly  in  the  interiors  of  the  trees. 

2.  At  picking  time  it  was  seen  that  the  greatest  blotch  infection 
on  the  sprayed  trees  appeared  on  the  fruit  located  on  the  interior 
parts  of  the  trees,  where  the  foliage  was  very  dense.     The  sprays 
would  doubtless  have  been  more  effective  if  the  trees  had  been  thoroly 
pruned.     On  blotch-infected  trees  water  sprouts  are  usually  more 
seriously  effected  by  the  disease  because  the  fungus  seems  to  thrive 
better  on  such  new,  tender  wood.     Thoroness  of  application  to  the 
interior  of  the  tree  is  therefore  essential;  the  spray  should  cover 
not  only  the  fruit  and  foliage  but  also  the  new  growth  in  order  to 
prevent  the  formation  of  cankers  thereon.    When  spraying  trees  for 
blotch,  pressures  of  200  to  225  pounds  should  be  used  and  the  man 
on  the  ground  should  direct  the  spray  to  the  interior  parts  of  the 
trees  and  to  the  undersides  of  fruit  and  branches. 

3.  Some  spray  injury  to  foliage  resulted  from  the  use  of  both 
Bordeaux  and  lime  sulfur. 

4.  Lime  sulfur  arsenate  of  lead  applied  during  the  hot  weather 
of  mid-July  caused  a  negligible  amount  of  burn  on  the  fruit;   that 
the  injury  was  not  greater  was  probably  due  to  the  fact  that  the 
trees  were  not  drenched. 

EXPERIMENTS  IN  1917 

The  results  obtained  at  Flora  in  1916  had  thoroly  demonstrated 
that  before  the  most  thoro  and  effective  spraying  can  be  done  against 
blotch,  the  trees  must  be  pruned  so  as  to  open  up  the  tops.  The 
results  had  also  demonstrated  that  cankered  water  sprouts,  which 
are  usually  a  serious  source  of  infection,  should  be  removed.  Accord- 
ingly this  work  was  thoroly  done  during  the  winter  of  1916-17  pre- 
paratory to  the  experiments  of  1917. 

The  experiments  of  1916  had  also  shown  that  125  pounds  pres- 
sure is  insufficient  if  a  fine  penetrating  spray  is  desired,  and  in  order 
to  obtain  high  pressures,  a  power  sprayer  was  secured  for  the  sea- 
son of  1917. 

Spraying  investigations  at  Flora  during  1917  were  conducted  to 
determine  the  following  points  in  the  control  of  blotch:  (1)  the  effect 
of  dormant  applications  of  copper  sulfate,  Scalecide,  lime  sulfur,  and 
lime-sulfur  copper-sulfate  mixture;  (2)  the  relative  value  of  Bor- 
deaux and  lime  sulfur;  (3)  the  value  of  different  applications  of 
Bordeaux  and  lime  sulfur;  (4)  the  effect  of  the  addition  of  arsenate 
of  lead  to  lime  sulfur;  and  (5)  the  relative  merits  of  dusting  and 
liquid  spraying. 


562 


BULLETIN   No.   222 


[September, 


TABLE  4. — EFFECTS  OF  DORMANT  APPLICATIONS  OF  COPPER  SULFATE,  SCALECIDE, 
LIME  SULFUR,  AND  LIME  SULFUR  COPPER  SULFATE  IN  THE  EXPERI- 
MENTS AT  FLORA,  1917 


Plat 

Treatment 

Applications1 

Total  No. 
picked  apples 

Percentage 
affected 
by  blotch 

1 
2 
3 
4 

5 
6 

7 
8 

Copper  sulf  ate  

1 
2,  3,  4,  5,  6,  7 

1580 
2010 
1468 

2500 
2471 

1891 
2960 
1986 

7.0 
14.0 
10.0 

16.0 
6.5 

9.0 
11.5 
9.5 

Lime  sulfur  arsenate  of  lead. 
Sealecide  

1 

2,  3,  4,  5,  6,  7 

1 
2,  3,  4,  5,  6,  7 

Lime  sulfur  arsenate  of  lead. 
Lime  sulfur  

Lime  sulfur  arsenate  of  lead. 

Lime  sulfur  copper  sulf  ate... 
Lime  sulfur  arsenate  of  lead. 

Lime  sulfur  arsenate  of  lead 
Copper  sulfate  

1 
2,  3,  4,  5,  6,  7 

2,3,4,5,6,7 

1 
2,3 

4,5,6,7 

1 
2,3 

4,5,6,7 

1 
2,3 
4,5,6,7 

Lime  sulfur  arsenate  of  lead. 
Bordeaux  arsenate  of  lead  .  .  . 

Sealecide  

Lime  sulfur  arsenate  of  lead 
Bordeaux  arsenate  of  lead  .  .  . 

Lime  sulfur  

Lime  sulfur  arsenate  of  lead. 
Bordeaux  arsenate  of  lead  .  .  . 

9 

Lime  sulfur  copper  sulfate  .  .  . 
Lime  sulfur  arsenate  of  lead 
Bordeaux  arsenate  of  lead  .  .  . 

1 
2,3 

4,5,6,7 

1504 

13.0 

10 
Check 

Lime  sulfur  arsenate  of  lead 
Bordeaux  arsenate  of  lead  .  .  . 

No  treatment  

2,3 
4,  5,  6,  7 

None 

1897 
1101 

8.5 
75.5 

"I:  Dormant,  March  31                4:  Three  weeks  after  fall  of  petals,  May  28 
2:  Cluster-bud,  April  20             5:  Five  weeks  after  fall  of  petals,  June  12 
3:  Fall  of  petals,  May  7             6:  Seven  weeks  after  fall  of  petals,  June  26 
7:  Ten  weeks  after  fall  of  petals,  July  17 

1919]  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  563 

EFFECT  OF  DORMANT  APPLICATIONS  OF  COPPER  SULFATE,  SCALECIDE, 
LIME  SULFUR,  AND  LIME-SULFUR  COPPER-SULFATE  MIXTURE 

Certain  apple  growers  in  this  state  had  expressed  the  belief  that 
a  dormant  application  of  lime-sulfur  or  copper-sulfate  solution  will 
reduce  blotch  infection,  presumably  by  destroying  the  cankers.  No 
experimental  evidence,  however,  was  available  on  this  point.  In  1907 
this  station  reported  on  tests  involving  the  spraying  of  bitter-rot 
cankers  with  copper-sulfate  solution  both  in  the  laboratory  and  in 
the  field.  The  results  of  such  experiments  demonstrated  that  bitter- 
rot  cankers  could  not  be  destroyed  by  an  external  application  of 
copper  sulfate.1  It  was  thought,  however,  that  since  the  mycelium 
of  blotch  fungus  works  just  beneath  the  bark  or  the  epidermis,  a 
dormant  spray  of  certain  soluble  materials  might  penetrate  the  dis- 
eased tissues  and  destroy  the  mycelium. 

In  conjunction  with  the  plat  tests,  the  results  of  which  are  pre- 
sented in  Table  4,  ten  one-year-old  blotch  cankers  on  water  sprouts 
were  sprayed  with  copper  sulfate,  Scalecide,  lime  sulfur,  and  lime- 
sulfur  copper-sulfate  mixture.  The  sprays  were  applied  on  March 
30  by  means  of  an  atomizer.  Ten  cankers  were  left  unsprayed  to  be 
used  as  checks. 

The  data  presented  show  that  a  dormant  application  of  copper 
sulfate,  Scalecide,  lime  sulfur,  or  lime-sulfur  copper-sulfate  mixture 
had  no  effect  on  the  blotch.  Plats  1,  2,  3,  and  4,  which  received  dormant 
applications  of  the  various  sprays  followed  by  summer  sprays  of 
lime  sulfur  arsenate  of  lead  showed  more  blotch  than  Plat  5,  which 
received  no  dormant  spray,  but  the  same  summer  applications.  A 
similar  difference  will  be  noted  between  Plats  6,  7,  8,  and  9,  which 
received  dormant  applications  of  the  various  spray  materials  followed 
by  summer  sprays  of  lime  sulfur  arsenate  of  lead  and  Bordeaux 
arsenate  of  lead,  and  Plat  10,  which  received  no  dormant  spray  but 
the  same  summer  applications. 

The  check  plat  showed  75.5  percent  blotch. 

These  results  were  further  substantiated  by  the  data  secured  from 
the  blotch  cankers  on  water  sprouts  sprayed  with  an  atomizer.  Ex- 
amination of  these  cankers  early  in  September  showed  that  in  no 
case  had  the  sprays  checked  the  growth  of  the  cankers.  The  cankers 
had  continued  their  growth  and  had  formed  new  pycnidia,  or  spore- 
bearing  cases,  and  altho  no  examinations  were  made  for  spores,  it  is 
reasonable  to  conclude  that  these  were  produced. 

RELATIVE  VALUES  OF  BORDEAUX  AND  LIME  SULFUR 

In  the  experiments  at  Flora  in  1916  Bordeaux  had  proved  superior 
to  lime  sulfur  in  the  control  of  blotch.  However,  as  the  orchard 
had  not  been  pruned  in  many  years,  it  had  been  impossible  to  make 

'111.  Agr.  Exp.  Sta.  Buls.  117  and  118.     1907. 


564 


BULLETIN  No.  222 


[September, 


S 

m           90 

r-i 

S 

i 

1 

« 

« 

to          o      o 

o 

eg* 

>*-> 

•>-* 

,0 

f-, 

0 

co 
eg 

t- 

,—  i 

^d 

CO 

eg 

05 

j 

_  P  t- 

rH 

j 

03 

-u 
§ 

in           in       o 

r-i               eo         r-i 

eo           eg 

Or?1"1 

0 

CD 

O> 

CO 

oTla  ^ 

rv. 

be 

CO 

ro 

"cj  ^j  oT 

rH 

< 

3 

-4->     p  !>"•"* 

H 

3 

M 

0) 

3 

.2 

10           m      m 

^f 

W 
EH 

3 

PH 

o 

CO 

eg 

O  •—  <  «H 
'cd    ® 

t-< 

M 

-1 

3 

.n          in      10 

*n   m   °* 

V  Cf^     FH 

H 

H 

1 

«o           od       in 

ij  c3  -S 

E 

5 

b» 

c3          *W 

X 

H 

p 

1 

9  *9  a 

'S    Q^  j-M 

a 

w  ^  S 

n 

0 

1 

•* 

B 

1 

1 

S  ^ 

» 

< 
S 

!1 

i* 
k 

O                rH         rH 

>    t>    p 

M 

_   r 

1 

in                rH         O 

rH  02  EH 

T  r; 

r 

eg                rH         rH 

P 

-t 

o  c 

i 

i 

rH                eg          rH 

Th  IO  «0 

9 

E 

nl 

\ 

p 

1 

L 

CQ 

W 

!»                <O 

*tn 

H 

0 

in"          to* 

rH 

0 

0 

s 

"rt 

0 

p 
eo           eo        o 

eg~     eg           * 

H 

S 

r-T              ? 

00 

p 

<5 

eg 

B 

M 

03 

O 

^^ 

pci 

oT 

b 

"e3 

O 

03 

eS        eS  _ 

<P          V  ro 

Pi 

«H 

O 

<M           «l-l     ® 

B 

p 

o       o1^ 

1—  1 

T. 

to 

QJ 

! 

0 

o       0  *o 

-M       ^»   s 

CQ            CO    ffl 

fl               0    ^j 

CD     rH 

^  ^  -2 

N 

fn 

CO             $     § 

S      b  o>     +j 

PH    ..^ 

<J    M    05 

n 

^      *  S      1 

^  03    TO 

5      5s*      P 

EH 

<H         «H    M          -S 
"9         3    3           « 

•1    ^| 

OQ            QQ    O)             5* 

^*0    & 

111       o 

§s  £ 

J           J  W            <H 

OPnEn 

^ 

mo            t> 

rH                 V 

rH  eg  eo 

6 

SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  565 

thoro  applications  and  it  was  thought  that  with  good  pruning  the 
results  might  be  different.  As  previously  stated,  the  trees  were  well 
pruned  during  the  winter  of  1916-17  and  in  1917  tests  were  again 
made  with  Bordeaux  and  lime  sulfur.  Sprays  were  applied  at  225 
pounds  pressure. 

The  results  in  Table  5  show  that  lime  sulfur  was  slightly  superior 
to  Bordeaux  in  the  control  of  blotch,  but  the  difference  is  so  slight 
that  both  sprays  may  be  considered  equally  effective. 

The  presence  of  russet  on  the  fruit  of  both  Plat  5  and  Plat  10 
is  a  rather  interesting  point.  Bordeaux  russet  is  a  common  form  of 
fruit  injury;  lime-sulfur  russet,  however,  is  unusual.  It  will  be 
seen  by  deducting  the  percentages  of  russet  present  on  the  unsprayed 
row  from  those  on  the  sprayed  plats  that  lime  sulfur  caused  30.5 
percent  slight  russet  and  Bordeaux  14  percent  serious  and  22.5  per- 
cent of  slight  russet. 

Lime  sulfur  caused  2.5  percent  serious  and  1.5  percent  slight  burn. 
This  injury  followed  the  application  made  ten  weeks  after  the  fall 
of  the  petals,  during  very  warm,  dry  weather. 

VALUE  OF  DIFFERENT  APPLICATIONS  OF  BORDEAUX  AND  LIME  SULFUR 

Experiments  conducted  at  Flora  in  1916  had  shown  that  the  most 
important  Bordeaux  and  lime-sulfur  sprays  for  blotch  were  those 
applied  three  and  five  weeks  after  the  fall  of  the  petals;  that  when 
applied  seven  weeks  after  the  fall  of  the  petals,  these  sprays  were  of 
less  value.  It  had  also  been  found  that  lime  sulfur  applied  ten  days 
after  the  fall  of  the  petals  exerted  no  control  over  blotch.  As  a  further 
test  of  the  value  of  different  applications  of  lime  sulfur  and  Bor- 
deaux as  sprays  for  blotch,  plats  were  sprayed  in  1917  as  shown  in 
Table  6. 

The  results  presented  for  Plats  11  and  12  and  Plats  16  and  17 
show  that  the  most  important  lime-sulfur  and  Bordeaux  sprays  against 
blotch  were  those  applied  three  and  five  weeks  after  the  fall  of 
the  petals.  Such  information  confirms  results  obtained  at  Flora 
in  1916.  These  facts  emphasize  the  importance  of  timeliness  of  appli- 
cation. It  will  be  noted  further  that  lime  sulfur  applied  seven,  ten, 
and  twelve  weeks  after  the  fall  of  the  petals  caused  some  reduction 
in  the  amount  of  blotch.  It  is  to  be  remembered  that  the  greatest 
blotch  infection  occurs  from  four  to  six  weeks  after  the  fall  of  the 
petals,  but  that  scattering  infections  may  take  place  thruout  the  rest 
of  the  season,  or  young  apples  infected  early  may  become  a  source 
of  later  infection  to  fruit  and  wood.  Such  conditions  may  explain 
the  control  exerted  by  spray  applied  seven,  ten,  and  twelve  weeks 
after  the  fall  of  the  petals.  Similar  results  were  obtained  from 
Bordeaux  applied  seven  and  ten  weeks  after  the  fall  of  the  petals. 


566 


BULLETIN   No.   222 


[September, 


i  1 

*  1 

to         to         to         to         to            to            to 

oo                oo                oi                oo                oo                    I-H                    IH 

CM                       CM                       CM                       CM                       CM                              CO                              CM 

o  W 

<O 

ctd          ^ 
e8         J 

§>    1 

1 
B 

O                     to                     to                     to                     O                            to                            <P 

oi                eo                CM'                co                t>^                    CM                    to 

CO                       CO                       <M                       i-H                       CM                              M*                              CO 

B 
B 

AH      ^ 

I 

O                       O                       to                       O                       O                              to                              to 

CD                     r-5                                              ^                     O                            O                            OS 

.s 
}f  "s 

O                       O                       r-l                       b-                       rH                              CO                              rH 
i-H                         O                         CO                         i-H                         iH                                iH                                b- 
OJ                         rH                         CO                        CO                         O                                to                                CO 
CM                       CM                       i-H                       i-H                       CM                              i-H                              CM 

Applications* 

<» 
t-                                                      fr-                 t-                                t-                                fc-                                fc- 

CO 

to                                                                                          to 

co~                co"                co"                co"                co"                co                     co 
CM"               CM"               CM"               cxT               CM"               CM"                   CM" 
i—  i                i—  i                i—  i                i—  i                i—  i                i—  i                     i—  i 

i 

•O'             'O'             'O*             "O*             'O*             •    o  ^      '             '    O~ 

*                                                                                      *              *                                                     *H                                *W 

s 

5  c^             .2  ® 

43 

03 

•    03*              .     -.       .              •     ..       .              «O3»              .     .,       ,              .     ..     -         .               *O3^ 

E 

H 

•    CD  rQ             •    O  r^J              •    Qj  r^              •    Ct)  r^              •    QJ  r^              »CUc3r^              •QJcS1^ 
•^,C3               '^03               *>nO3               *^(O3               *^O3               *tnflc3                "f_t^Cd 

33o        tS^O        eS^3®          ^^o          3PQ          33raQ          33o 

335     335     335     335     335     33§5     33§5 

cooajj         DQcQcj         '•'•>-    r.         """Ooj         CQtOjj         °°coo3c3          cocooSoS 

ill  n§  ill  ill  ni  nil  ml 

J  J  <J       J  J  <j       13  h4  <1       J  iJ  •<       J  J  <J       v3  J  CQ  <l       J  |j  03  <J 

K 

rH                       CM                       CO                       •*                       to                       CO                             b- 
f-l                     i-H                     rH                     i-l                     rH                     rH                           r-l 

SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH 


567 


o 
ci 

co 


0 
(0 


ijji  :::•  i 

£         * 

•  '""'  OS  •  •>~'o3' 

o  ~*    • 

"=«    <»      • 

«  "d  TJ 

59   fl   cS 

•  0*0  '  *  ^"0  ' 

•VoS'C  'SoSTJ 

•  S  a  cs  •  s?  «  as 

O>    <B 
~     00  •— ' 

ss^ 

fi.fi    M 

g-3  S^ 

«   oo    cS    oS 

2  2?  § 

g  S  ^  to 
"  .S  o  ^ 


•  3  S  "> 

*u      02    r— I 

I^S^ 

s^  Ss 

«   <»   cS   S 

§§?§ 

.§  .§  o  £ 

j  j  pa  <d 


=8  £3 


O     »   rg 

a  si 

.—  .-   o 
J  J  CQ 


•<*  (M  00 


568  BULLETIN   No.   222  [September, 

It  will  be  noted  that  Bordeaux  applied  twelve  weeks  after  the  fall 
of  the  petals  was  of  practically  no  value  in  controlling  blotch. 

By  deducting  the  amount  of  russet  on  the  unsprayed  row  from 
that  present  on  the  sprayed  plats,  the  true  amount  of  russet  caused 
by  the  sprays  may  be  found.  It  is  difficult  to  say  definitely  which 
application  of  lime  sulfur  caused  the  russet  on  Plats  11,  12,  13,  14, 
and  15,  altho  it  is  probable  that  it  was  caused  by  the  application 
made  at  the  fall  of  the  petals,  since  all  the  lime-sulfur  plats  have 
practically  the  same  amounts  of  russet. 

Plat  16,  sprayed  with  Bordeaux  at  the  fall  of  the  petals,  showed 
considerable  russet.  This,  no  doubt,  was  caused  partly  by  lime  sulfur 
applied  at  the  fall  of  the  petals  and  partly  by  Bordeaux  applied 
three  weeks  later.  The  russet  on  Plats  17,  18,  19,  and  20  was  prob- 
ably due  to  lime  sulfur  applied  at  the  fall  of  the  petals  and  not  to 
later  Bordeaux  sprays. 

EFFECT  OF  THE  ADDITION  OF  ARSENATE  OF  LEAD  TO  LIME  SULFUR 

In  experiments  conducted  by  the  writer  in  1912,  it  had  been  found 
that  the  addition  of  arsenate  of  lead  to  lime  sulfur  slightly  increased 
its  value  as  a  spray  for  scab.1  It  has  been  somewhat  of  a  question 
whether  such  an  addition  would  increase  the  value  of  lime  sulfur 
as  a  spray  for  blotch.  To  determine  this  point  three  plats  were 
treated  as  shown  in  Table  7.  The.  first  three  applications,  made  for 
the  control  of  scale  and  scab,  were  the  same  on  all  plats. 

The  results  presented  show  that  Plat  21,  which  was  sprayed  three, 
five,  seven,  and  ten  weeks  after  the  fall  of  petals  with  arsenate  of 
lead  alone,  had  56  percent  blotch;  Plat  22,  sprayed  at  these  times 
with  lime  sulfur  alone,  17  percent  blotch;  and  Plat  23,  sprayed  at 
the  same  times  with  lime  sulfur  arsenate  of  lead,  19  percent  blotch. 
That  arsenate  of  lead  alone  had  some  value  as  a  spray  for  blotch 
is  seen  when  reference  is  made  to  the  percentage  of  blotch  on  the 
unsprayed  row,  but  its  addition  to  lime  sulfur  can  hardly  be  said 
to  increase  the  value  of  that  spray  in  the  control  of  blotch. 

RELATIVE  MERITS  OF  DUSTING  AND  LIQUID  SPRAYING 

In  order  to  gain  definite  information  with  regard  to  the  com- 
parative values  of  dusting  and  liquid  spraying  in  the  control  of  blotch, 
plats  were  treated  as  shown  in  Table  8. 

The  results  presented  show  that  dusting  with  a  mixture  of  finely 
ground  sulfur  and  powdered  arsenate  of  lead  failed  to  exert  any  con- 
trol over  blotch,  while  sprays  of  lime  sulfur  arsenate  of  lead  reduced 
the  infection  from  75.5  percent  on  the  unsprayed  row  to  10  percent. 

'111.  Agr.  Exp.  Sta.  Bui.  185,  p.  185. 


1919] 


SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OP  BLOTCH 


569 


TABLE  7. — EFFECTS  OF  THE  ADDITION  01  ARSENATE  OF  LEAD  TO  LIME  SULFUR  AS 
A  SPRAT  FOR  BLOTCH  IN  THE  EXPERIMENTS  AT  FLORA,  1917 


Plat 

Treatment 

Applications1 

Total  No. 
picked  apples 

Percentage 
affected 
by  blotch 

21 

Lime  sulfur    

1 

Lime  sulfur  arsenate  of  lead  .  . 
Arsenate    of   leftd  

2,3 

4,  5,  6,  7 

970 

560 

22 

Lime   sulfur    

1 

Lime  sulfur  arsenate  of  lead  .  . 

2,3 
4,  5,  6,  7 

1250 

17.0 

23 

1 

Lime  sulfur  arsenate  of  lead  .  . 

2,  3,  4,  5,  6,  7 

972 

19.0 

Check 

No  treatment  

None 

1101 

75.5 

*1:  Dormant,  March  30 

2 :  Cluster-bud,  April  21 

3:  Fall  of  petals,  May  8 

4:  Three  weeks  after  fall  of  petals,  May  25 

5:  Five  weeks  after  fall  of  petals,  June  13 

6:  Seven  weeks  after  fall  of  petals,  Jun.e  27 

7:  Ten  weeks  after  fall  of  petals,  July  18 


TABLE  8. — EFFECTS  OF  DUSTING  AND  Li  QUID  SPRAYING  IN  THE  EXPERIMENTS  AT 

FLORA,   1917 


Flat 

Treatment 

Applications1 

Total  No. 
picked  apples 

Percentage 
affected 
by  blotch 

A 

3 

Check 

Lime  sulfur   

1 
2,3,4,5,6,7 

1 
2,3,4,5,6,7 

None 

1417 

1586 
1101 

83.5 

10.0 
75.5 

Sulfur-arsenate    of    lead    dust 
(85-15)    . 

Lime  sulfur    

Lime  sulfur  arsenate  of  lead  .  . 
No   treatment    

*1:  Dormant,  March  29 
2:  Cluster-bud,  April  19 
3:  Fall  of  petals,  May  9 
4:  Three  weeks  after  fall  of  petals,  May  28 
5:  Five  weeks  after  fall  of  petals,  June  15 
6  :  Seven  weeks  after  fall  of  petals,  June  28 

7:  Ten  weeks  after  fall  of  petals,  July  17 


570  BULLETIN   No.   222  [September, 

SUMMARY  OF  RESULTS  FOR  1917 

1.  Dormant  applications  of  copper  sulfate,  Scalecide,  lime  sulfur, 
and  lime-sulfur  copper-sulfate  mixture  were  valueless  in  checking 
blotch.    Blotch  cankers  on  water  sprouts  continued  to  grow  and  form 
pycnidia  after  being  sprayed  with  these  materials. 

2.  Lime  sulfur  and  Bordeaux  were  practically  equally  effective 
in  their  control  of  blotch. 

3.  Both  lime  sulfur  and  Bordeaux  russetted  the  fruit,  the  former 
in  the  application  made  at  the  fall  of  the  petals  and  three  weeks 
later,  and  the  latter  in  the  spray  applied  three  weeks  after  the  fall 
of  the  petals. 

4.  Applications  of  lime  sulfur  and  Bordeaux  made  three  and 
five  weeks  after  the  fall  of  the  petals  were  the  most  important  sprays 
in  the  control  of  blotch.    Lime  sulfur  exerted  the  greater  degree  of 
control.    Applications  of  these  materials  made  seven,  ten,  and  twelve 
weeks  after  the  fall  of  the  petals  were  of  decidedly  less  value  in 
controlling  blotch. 

5.  Arsenate  of  lead  alone  possessed  some  value  as  a  spray  for 
blotch,  but  the  addition  of  this  material  to  lime  sulfur  did  not  in- 
crease the  value  of  that  spray  in  the  control  of  blotch. 

6.  Dusting  with  a  mixture  of  85  pounds  of  finely  ground  sulfur 
and  15  pounds,  of  powdered  arsenate  of  lead  was  valueless  in  con- 
trolling blotch,  while  liquid  lime  sulfur  arsenate  of  lead  gave  good 
results. 

INCIDENTAL  OBSERVATIONS 

1.  The  experimental  work  at  Flora  in  1917  again  emphasized 
the  importance  of  pruning  trees  infected  with  blotch.    Pruning  out 
dead  wood,  crossing  branches,  and  water  sprouts  facilitated  spraying. 
Blotch   cankers   develop   more   readily   on  water  sprouts,   thus  in- 
creasing the  danger  of  infection  on  fruit  and  new  growth.     They 
should  therefore  be  removed. 

2.  Timeliness  of  application  is  the  first  essential  in  controlling 
blotch.     Thoroness  is  the  next  important  item  and  this  can  be  at- 
tained only  by  means  of  high  pressures,  200  to  225  pounds,  using 
discs  with  small  openings  that  will  produce  a  fine  mist.    Trees  should 
be  sprayed  in  the  interior  and  underneath  as  well  as  from  the  outer 
sides. 

3.  Apple  blotch  was  first  observed  on  the  unsprayed  fruit  on 
June  12,  five  weeks  after  the  fall  of  the  petals. 

4.  Blotch  must  be  controlled  by  the  sprays  three  and  five  weeks 
after  the  fall  of  the  petals,  for  it  cannot  satisfactorily  be  controlled 
by  sprays  applied  later  in  the  season. 


1919]  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  571 

5.  Both  Bordeaux  and  lime  sulfur  caused  some  foliage  injury. 
Injury  from  Bordeaux  appeared  as  brown  spots  and  later  as  tip 
and  edge  burn.     Vigorous  trees  suffered  less  spray  injury  to  the 
foliage  than  weak  trees. 

6.  Dusting  trees  was  not  as  efficient  as  liquid  spraying  in  the 
control  of  blotch  and  was  much  more  expensive. 

7.  The  Friend  spray  gun  was  found  to  be  wasteful  as  it  gave  a 
much  coarser  spray  than  the  ordinary  disc  nozzles. 

EXPERIMENTS  IN  1918 

The  season  of  1918  at  Flora  proved  very  discouraging  not  only 
to  experimental  workers  but  to  commercial  growers  as  well.  The 
blooming  period  of  Ben  Davis  extended  over  a  period  of  ten  days 
in  the  Suggett  orchard,  during  which  time  the  weather  was  cool 
and  very  wet.  A  light  set  of  apples  resulted  in  all  but  a  few  rows 
on  the  west  side  of  the  orchard.  Following  such  unfavorable  con- 
ditions for  pollination  came  the  ten-weeks  drouth  of  June,  July,  and 
August,  which  materially  reduced  the  size  of  the  apples. 

It  was  possible  to  obtain  records  only  on  the  plats  which  were 
concerned  with :  (1)  the  relative  values  of  Bordeaux  and  lime  sulfur 
as  sprays  for  blotch;  and  (2)  the  value  of  different  applications 
of  Bordeaux  and  lime  sulfur  as  sprays  for  blotch. 

RELATIVE  VALUES  OF  BORDEAUX  AND  LIME  SULFUR 

Results  of  experiments  in  1917  had  shown  that  Bordeaux  and  lime 
sulfur  were  equally  effective  in  the  control  of  blotch.  Further  com- 
parison of  these  two  sprays  was  made  in  1918  with  the  results  pre- 
sented in  Table  9. 

These  data  show  that  Bordeaux  and  lime  sulfur  were  practically 
equal  in  the  control  of  blotch.  It  will  be  noted  that  Plat  1  shows  5 
percent  more  blotch  than  Plat  2,  which  difference  may  have  been 
due  to  the  omission  of  the  spray  seven  weeks  after  the  fall  of  the  petals. 

Results  for  Plats  3  and  4  show  practically  an  equal  amount  of 
blotch.  It  is  very  probable  that  the  Bordeaux  applied  to  Plat  4  seven 
weeks  after  the  fall  of  the  petals  was  unnecessary,  owing  perhaps  to 
the  adhesiveness  of  the  spray  applied  five  weeks  after  the  fall  of 
the  petals.  Blotch  was  greatly  reduced  on  all  the  sprayed  plats, 
since  94  percent  infection  appeared  on  the  unsprayed  row. 

Reference  to  the  russet  column  will  show  that  both  lime  sulfur 
and  Bordeaux  caused  some  russet,  but  more  serious  russeting  occurred 
on  the  plats  sprayed  with  Bordeaux  than  on  those  sprayed  witlflime 
sulfur. 


572 


BULLETIN  No.  222 


[September, 


1 

S 

0               O                     O                     O         0 

L 

| 

02 

0 

« 

1 

o          o              o              o      o 

i 

o 

in 

I—  1 

"co 

rt 

0 

02 

rH           J- 

OO 

CO 

205  5 

rH 
C5 
rH 

CJ 

"SL 

IS 

o          to              o              iq      o 

1-3 

_ 

c3 

tc 

eo           t^               i>               ^      i-i 

**       •—  5 

< 

'^ 

rH                                                                 rH 

CO       ^  CO 

« 

». 

"tn 

O2 

~  .    i    QJ 

S 

0 

S 

'w  ^  ft 

PH 

H 
3j 

8> 

a 

M 

OQ 

3 

.2 

O               IA                     O                     O         O 

•<$           rA               d               eo 

P<    SJ    5|_| 
O  «H  rH 

02 

<o 

o 

rH                       rH 

^g  ^j  *H 

EH 

w 

02 

*H    rt    fn 

2 

0 

t-«  ^^   •*-* 

H 

5 

PH 

3 

S 

•1 

} 

O               O                     O                     O_         O 

'eS  *"    a) 

H 

E 

H 

1 

5 

IO               O                     O                     00         *^ 

rH                rH                       rH                                     O5 

03     *   "g 

W 

P 

5 

^    co   Q^ 

W 

>   cp 

W 

Ig 

w 

tH 

or 

a 

• 

"   P)   * 

g 

i 

'   C 

1 

-i 

0               >0                     t-                     10         t- 

jcnS 

g 

^ 

^ 

O               rH                     OO                     OO         00 

•^               O                      "^                     CO         C3 

1C  «O  t- 

* 

5   a 

iJ 

P 

e 

H-t 

02 

H 

H 

g 

r— 

t~               t-                     b>                     t> 

rH 

Tn 

0 

O 

0 

«o          «o              o              ^ 

55 

•< 

"S 

CJ 

10s                                             lo"               © 

•*                 **                       **                       "*               fl 

M 

•»          \,              \«.             \,         iS 

P 

"E, 

co           eo                co                co           J^ 

< 
H 

^ 

of          of          «                oa 

<M 

0 

^» 

»*             ^             »»                 ^ 

^O 

M 

rH                  rH                 rH                         rH 

fc^ 

O 

rt   ® 

§ 

J* 

0} 

Ptj 

fe 

B              9              fl  ^              ^  ^ 

«H 

* 

v             o             a>  ci             cJ  rt 

o  CM 

H 

1 

H                     —1                     i—  c     QJ                     r-1     Q3 

O                O                O  ^                O  «,_, 

^  o 

o 

O) 

1 

5         ^         ^  °         ^  ° 

CS           1H 

W 

| 

CQ  ^^             Co                     C3     O                     CJ     O 

"C  ^5  .S  ^ 

3 

« 

« 

M 

S03         rort         roflrt         Sflrt 

^•H     »^  ;lj  •*"* 

•« 

H 

^!  ,^H          rt 

&H 

&               ci                *-    /•                cd    GO 

-.2  ^ 

M     ^J                       rH     ^^                       rH        rt     ^^                       rH        C3      T^ 

po       po       p       o       p       °M 

1  ftS-i 

"95            35            ^P^            ^P-2              rl 

A  "g  ^  1 

oocS         <«ca         wa3c4         ooojcd         rt 

S,     • 

S<n        Sen        S^ro        S^-oo        co 
•B   »-j        .S  JH        .3   O   (-1        .S   O   f-i         B 

slkls 

"S 

M 

M 

S 

H          oq           eo               ^Jt                a) 

6 

1919]  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  573 

Plat  2  showed  1  percent  of  burn,  which  resulted  from  lime  sulfur 
arsenate  of  lead  applied  ten  weeks  after  the  fall  of  the  petals  during 
very  warm,  dry  weather. 

VALUE  OF  DIFFERENT  APPLICATIONS  OF  BORDEAUX  AND  LIME  SULFUR 

Experiments  were  continued  to  obtain  further  information  with 
reference  to  the  value  of  different  applications  of  Bordeaux  and 
lime  sulfur  in  the  control  of  blotch.  The  results  are  shown  in  Table  10. 

Eeference  to  the  results  for  Plats  5  and  9  will  show  that  lime 
sulfur  or  Bordeaux  applied  three  weeks  after  the  fall  of  the  petals 
gave  the  most  effective  control  over  blotch.  Applications  of  these 
materials  five  weeks  after  the  fall  of  the  petals  were  next  in  effective- 
ness, while  sprays  applied  seven  and  ten  weeks  after  the  fall  of  the 
petals  were  of  less  value. 

The  amounts  of  russet  on  the  different  plats  is  rather  incon- 
sistent in  variation,  but  there  is  no  doubt  in  the  writer's  mind  that 
both  lime  sulfur  and  Bordeaux  caused  some  russeting  of  the  fruit. 

No  burn  was  recorded. 

SUMMARY  OF  RESULTS  FOR  1918 

1.  Bordeaux  and  lime  sulfur  were  practically  equal  in  the  control 
of  apple  blotch. 

2.  The  most  important  application  of  lime  sulfur  or  Bordeaux 
was  three  weeks  after  the  fall  of  the  petals;  and  the  second  in  im- 
portance, five  weeks  after  the  fall  of  the  petals.    Later  applications 
were  of  little  value  in  reducing  blotch  infection. 

INCIDENTAL  OBSERVATIONS 

1.  The  importance  of  thoroness  and  timeliness  of  application 
in  spraying  for  blotch  was  further  emphasized  in  the  work  at  Flora 
in  1918. 

2.  Friend  and  Ward  spray  guns  were  both  used.    It  was  found 
that  the  latter  type  gave  the  finer  mist,  but  neither  makes  developed 
as  fine  a  mist  as  that  produced  by  ordinary  disc  nozzles. 

3.  Spray  guns  proved  wasteful,  applying  an  excess  of  material. 
More  lime-sulfur  injury  developed  on  the  foliage  of  trees  sprayed 
with  the  gun  than  on  those  sprayed  with  disc  nozzles. 

4.  The  trees  could  not  be  sprayed  properly  by  using  one  spray 
gun  operated  from  the  top  of  the  tank.    They  were  more  advantage- 
ously sprayed  by  using  a  rod  and  disc  nozzle  in  the  tower  and  a 
rod  and  two  disc  nozzles  on  a  Y,  for  ground  spraying,  than  by  using 
a  rod  and  disc  nozzle  in  the  tower  and  a  spray  gun  for  ground 
spraying. 


574 


BULLETIN   No.   222 


[September, 


oo  o  o 


oo  o  o 


03 


o<          o 

«O  00 


A* 


•g 

-(-> 
o 

s 


IH  'W 

5  o- 


5  ° 

CS    (V 


e 

c3 


eg 

cdai 


coctfcS 

«^§g     -S 
.S  §  2      o 


1919]  SPRAYING  APPLE  ORCHARDS  FOR  CONTROL  OF  BLOTCH  575 

5.  Apple  blotch  was  first  observed  on  the  unsprayed  fruit  on 
June  19,  seven  weeks  after  the  fall  of  the  petals. 

6.  Unhealthy  apple  trees  suffered  more  serious  spray  injury  to 
foliage  than  vigorous  trees. 

RECOMMENDATIONS  FOR  THE  CONTROL  OF  APPLE 

BLOTCH 

The  first  step  to  take  in  the  control  of  apple  blotch  is  to  remove 
water  sprouts  as  they  are  very  susceptible  to  blotch  infection.  Fol- 
lowing this  the  tops  of  the  trees  should  be  well  pruned  so  as  to  permit 
thoro  spraying. 

High  pressures,  from  225  to  250  pounds,  should  be  used,  driving 
the  spray  thru  disc  nozzles  with  small  openings.  Discs  should  be 
replaced  whenever  the  openings  wear  too  large  to  give  the  finest 
mist  spray. 

Trees  should  be  sprayed  thoroly  but  not  drenched  and  care  should 
be  taken  to  apply  the  spray  to  the  new  wood  as  well  as  to  the 
fruit.  The  interior  and  under  parts  of  the  trees  should  be  well 
sprayed. 

Sprays  should  be  applied  on  time,  not  on  certain  dates,  but 
with  reference  to  the  time  of  the  fall  of  the  petals. 

The  following  schedule  is  recommended  for  blotch-infected 
orchards : 

First  Application. — The  first  and  most  important  spray  for  apple 
blotch  is  that  applied  as  near  to  three  weeks  after  the  fall  of  the 
petals  as  possible.  Lime  sulfur  arsenate  of  lead  should  be  used  at 
the  rate  of  2,y2  gallons  of  lime  sulfur  and  2  pounds  of  powdered  or 
4  pounds  of  paste  arsenate  of  lead  in  100  gallons  of  water. 

Second  Application. — A  second  and  important  application  of  lime 
sulfur  arsenate  of  lead  should  be  applied  two  weeks  later,  or  five 
weeks  after  the  fall  of  the  petals. 

If  apple  blotch  is  to  be  controlled  by  spraying,  the  fruit  must 
be  protected  during  the  period  from  four  to  six  weeks  after  the 
fall  of  the  petals,  because  this  is  the  time  of  greatest  infection.  Ap- 
plications made  three  and  five  weeks  after  the  fall  of  the  petals  will 
accomplish  this  protection,  provided  heavy  rains  do  not  occur.  In 
the  event  of  heavy  rains  following  such  applications,  it  will  be  neces- 
sary to  apply  extra  sprays  of  lime  sulfur.  Bordeaux  is  more  adhesive 
than  lime  sulfur  but  the  danger  from  russet  on  Ben  Davis  at  these 
periods,  especially  during  wet  weather,  makes  the  use  of  lime  sulfur 
more  desirable. 


UNIVERSITY  OF  ILLINOIS-URBAN* 


